Engine fan won’t shut off!

Discussion in 'International Forum' started by CraigInReston, Aug 31, 2020.

  1. CraigInReston

    CraigInReston Light Load Member

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    Hi guys, looking for some advise again. I have a 2011 International 9900 with a CM871 ISX. Truck was parked a few months and after finishing a full service, the engine fan won’t shut off. I’ve checked coolant sensor, fan solenoid (which only shows 11.3volts), air is reaching fan hub and it locks when disconnecting solenoid connector. Many people say a/c high pressure switch, both the high and low are located just below the passenger seat, outside above steps. When I took plastic cover off to expose high/low switches, the wiring has me baffled! The high and low switches are connected together, with a third separate set of wires running through the floorboards to the evaporator under the passenger seat? Question is... how in hell are the pressure switches receiving power? Or did someone hook the connectors backwards?
     
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  3. Heavyd

    Heavyd Road Train Member

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    If air is reaching it, it should unlock at that point. Does it unlock with air? To further check your ac, I need to know if you have the APADS system on it or not. APADS is little electronic module with a red and green LED light on it mounted near the firewall at the drivers side.
     
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  4. CraigInReston

    CraigInReston Light Load Member

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    Yes, I have APADS and neither green or red lights are on. I did the 4x on/off reset, still nothing is on.
     
  5. CraigInReston

    CraigInReston Light Load Member

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    When it’s aired up, I can hear clutch disengage and spin fan manually, when disconnecting connector at the fan solenoid. Testing voltage at solenoid reads 11.3volts.
     
  6. Heavyd

    Heavyd Road Train Member

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    No lights means it isn't getting any power, or completely failed unit. A quick test is there should be battery power at key on at the red wire. Ground is the solid black wire. Fan control signal input to the ECM is the orange wire. I think the way the it works is the apads module will ground this wire which the ECM will see and when the ECM sees a ground it turns the fan off. So an open wire or failed apads would cause the fan to be on all the time. If you unplug that apads connector and ground the wire that would connect to the orange apads wire, the fan should turn off after about 2-3 minutes. The wire you are looking for is 23AC, tan in colour.
     
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  7. CraigInReston

    CraigInReston Light Load Member

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    Exactly what you said. There’s 12.8volts with key on at red wire. Grounded tan wire which only read 5.8volts to frame, about 1 min later fan shut off.
     
  8. CraigInReston

    CraigInReston Light Load Member

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    What now? Bad APADS?
     
  9. Heavyd

    Heavyd Road Train Member

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    Yes. Failed module.
     
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  10. CraigInReston

    CraigInReston Light Load Member

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    Thanks again HeavyD. You’re the man!
     
    Heavyd Thanks this.
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